Ideas about an analog-to-digital converter API

[Ken Hornstein <kenh%cmf.nrl.navy.mil@localhost>]

I've been thinking about writing a driver for the A/D converter hardware
in one of the ARM boxes that I have.  I have the documentation, and writing
that driver looks relatively straightforward.  But ... what I am having
a problem with is: what should the userspace API look like?

The easiest thing to do would be to simply create a sysctl node for
the A/D converter.  This is fine for many uses, but if you want to do
something more complicated (like, do a continuous series of samples
as fast as the converter hardware can go), then it is lacking.

I've looked around briefly, and I don't think I've seen a A/D converter
API used by other other Unixes.  If there was one, I'd probably use that as
a place to start cribbing from.  Does anyone know of any sample APIs, or
have any thoughts on a place to start?

(I'll probably at least start with a sysctl interface, just to make things
easy).

--Ken